The present invention relates generally to a system and method for generating output for computer systems, and more particularly to a system and method for modifying the presentation of structured documents.
The rapid expansion of the World Wide Web—where dynamic, compelling images are crucial—has driven the demand for a document format that preserves all of the fonts, formatting, colors, and graphics of any source document, regardless of the application and platform used to create it.
One such format is referred to as the portable document format (PDF). PDF is a file format developed by Adobe Systems, Incorporated. PDF captures formatting information from a variety of desktop publishing applications, making it possible to send formatted documents and have them appear on the recipient's monitor or printer as they were intended.
A source document can be authored in a page description language (PDL). PDL is a language for describing the layout and contents of a printed page. One well-known PDL is PostScript™ by Adobe Systems, Inc. PostScript describes a page in terms of page objects including textual objects and graphical objects such as lines, arcs, and circles. Moreover, PDF is a PDL.
According to conventional methods, a PDL document is rendered by first defining a bounding box, such as a page, and then placing the textual and graphical objects defined for the page into the bounding box according to the definitions in the PDL document. Normally the size of a PDL page is chosen so that it is clearly legible on a standard full-sized display. For example, an 8-inch page width may be chosen for display on a 15-inch computer monitor.
However, a single page size may not be ideal for devices having non-standard display sizes, such as a hand-held personal digital assistant (PDA). To view a PDL page having an 8-inch page width on a 3-inch-wide display, the user has two alternatives. The user can change the zoom factor of the display to show the entire page on the 3-inch display. However, this approach will generally render the page too small to be legible. Alternatively, the user can simply show a portion of the page at full magnification, and scroll horizontally and vertically to view the rest of the page. This approach is inconvenient and time-consuming.
Another approach is for the author of the PDL page to generate a different PDL page for each display size using the application that created the PDL page. This approach is wasteful because multiple copies of each PDL page must be maintained. In addition, the user must select the copy that is appropriate for the display on which the PDL page will be viewed.